Conventionally, various automotive headlamps with a structure having a semiconductor light emitting element and a light guide lens in combination have been proposed, for example, such as those disclosed in U.S. Pat. No. 7,460,985 (Benitez et al.).
FIG. 1 shows a perspective view of an automotive headlamp 200 which is disclosed in U.S. Pat. No. 7,460,985.
As shown, the automotive headlamp 200 can include a light guide lens 210 and a semiconductor light emitting element 220. It is conceivable that the light guide lens 210 could be used as an embodiment of the guide lens in the presently disclosed subject matter. The light guide lens 210 can include a front surface 212 to be disposed on the front side of a vehicle body, a rear surface 214 to be disposed on the rear side of the vehicle body, and a concave portion 216 including a light incident surface 218. The semiconductor light emitting element 220 can be disposed within the concave portion 216. The light incident surface 218 can be configured to surround the semiconductor light emitting element 220 so as to allow the light emitted from the semiconductor light emitting element 220 to be incident thereon efficiently.
The front surface 212 can reflect, toward the rear surface 214, the light emitted from the semiconductor light emitting element 220 and entering the light guide lens 210 through the light incident surface 218 while the front surface 212 can receive the light reflected by the rear surface 214 to allow the light to pass therethrough. The rear surface 214 can reflect the light reflected by the front surface 212 toward the front surface 212.
Specifically, the light emitted from the semiconductor light emitting element 220 can enter the light guide lens 210 through the light incident surface 218, be reflected by the front surface 212 and the rear surface 214, and then be projected through the front surface 212 forward. Therefore, the front surface 212, the rear surface 214 and/or the light incident surface 218 can be designed in surface shape so as to cause the light entering the light guide lens 210 through the light incident surface 218 and reflected by the front surface 212 and the rear surface 214 and then projected forward through the front surface 214 to form a predetermined light distribution pattern.
However, in the automotive headlamp 200 disclosed in U.S. Pat. No. 7,460,985, part of light emitted from the semiconductor light emitting element 220 does not enter the light guide lens 210 while being reflected by the light incident surface 218, and is therefore wasted without being utilized for the formation of the predetermined light distribution pattern. This can reduce the light utilization efficiency.